DC_Amazing Earth_9of9_Journey to the Centre of the Earth
Transcript
00:00:00Jules Verne thrilled the world with tales of fantastic journeys to the bottom of the
00:00:12ocean, the North and South Poles, and the moon.
00:00:20Back in the 19th century, none of his adventures was thought possible.
00:00:25Since then, we've realized them all, except one.
00:00:30Is science and technology finally ready to fulfill Verne's ultimate dream?
00:00:35Can we journey to the center of the Earth?
00:00:40Amiens, a small town near Paris, France, was home to one of the most visionary authors of all time.
00:00:57He's known as the father of science fiction.
00:01:01Some say he invented the future.
00:01:04He was Jules Verne.
00:01:07150 years ago, he wrote tales of adventure and science fantasy, much of which has become science fact.
00:01:19His heroes flew to the moon 100 years before the first real attempt and circumnavigated
00:01:25the globe in days at a time when it took months.
00:01:30Like all Verne's bestsellers, Journey to the Center of the Earth was a product of rich
00:01:36imagination and research.
00:01:39How much did his scientific crystal ball get right?
00:01:49When Verne was writing Journey, little was known about the interior of our planet.
00:01:55The Earth sciences were in their infancy.
00:01:59But the 19th century was a time of great discovery.
00:02:14Journey is set in 1864.
00:02:19Verne's heroes are German professor Otto Lindenbrock, his nephew Axel, and their Icelandic guide Hans.
00:02:29Their quest takes them to the center of the Earth and back through time.
00:02:37Verne's prehistoric monsters were the real thing, the underground ocean he invented.
00:02:46Science and technology, thrills and spills, no other writer captures so well the excitement
00:02:52of exploration and discovery.
00:02:56How much did he get right?
00:03:05Since Verne's time, we've conquered space.
00:03:08But if we are ever to journey to the center of the Earth, we still have a long way to go.
00:03:22Who hasn't as a child daydreamed about digging through the Earth and popping up on the other
00:03:27side of the world?
00:03:29If we could do this, where would we end up?
00:03:35Jumping into a hole in Spain would bring you out in New Zealand.
00:03:41Argentina would link to China.
00:03:46And from Miami, you could drop in on Perth, Australia.
00:03:52If these dream tunnels were real, you could just jump in and let gravity take over.
00:04:00Gravity would cause you to accelerate towards the center and then slow you down again, allowing
00:04:06you to step out on the other side 8,000 miles later.
00:04:15If we could dig a hole like this, what would we find?
00:04:19At the Earth's center is a massive ball of iron known as the core.
00:04:24An outer core of molten iron swirls around it.
00:04:28Next is the mantle, slow-moving hot rock 1,800 miles thick.
00:04:35In contrast, the crust, the part we live on, is thin.
00:04:41In fact, it's broken into pieces called plates.
00:04:50The crust's plates are always on the move.
00:04:55The journey down an eroded canyon is like a journey back in time because it shows how
00:05:00the Earth's crust has changed and continues to change.
00:05:06Layer upon layer of rock has built up on the surface of the Earth over millions of years
00:05:12and is relentlessly worn away by wind and water.
00:05:18But the deepest canyon on Earth is only two miles deep.
00:05:23It's 4,000 miles to the center of the Earth.
00:05:27But how far is that?
00:05:35This airplane is flying at 12,000 feet.
00:05:39The parachutists will fall 7,000 feet before opening their chutes.
00:05:50They free fall at over 100 miles an hour.
00:05:54At this speed, they'd reach the Earth in just over a minute.
00:05:58If they could continue like this to the center of the Earth, it would take over 36 hours.
00:06:05It's as far as Chicago to London.
00:06:15Caves were an obvious starting point for a journey to the center of the Earth.
00:06:20The deepest cave Verne knew of was at Huachara, Colombia.
00:06:25It had been explored to 2,500 feet.
00:06:30Not one for half measures, Verne wondered,
00:06:33what would happen if his explorers went much deeper?
00:06:45Jules Verne reveled in technological invention
00:06:48and outfitted his heroes with electric lights powered by chemicals.
00:06:54He knew naked flames were a hazard underground
00:06:57and came up with this original solution at a time when gas light was still a luxury
00:07:02and electricity known only to scientists.
00:07:10The geologists of the day thought that erupting volcanoes must leave giant tunnels underground.
00:07:21Verne was fascinated by geology
00:07:24and led his explorers past rich seams of minerals and precious metals
00:07:32and into cathedrals of stalactites and stalagmites built of lime by a billion water drops.
00:07:46Caves had been tourist attractions since the beginning of the 1800s.
00:07:51Verne used these as a route to the Earth's center, but not caves like this.
00:08:02Modern caving began in the 1880s, directly inspired by journey.
00:08:10Pioneering cavers didn't have the high-tech gear we take for granted.
00:08:15Wetsuits were unknown.
00:08:18Instead of lightweight alloys, their tools were made of steel by blacksmiths.
00:08:26They made their own ropes from hemp or silk, not waterproof man-made fibers,
00:08:32and had to hire porters to carry all the heavy equipment.
00:08:37Today, caving is more popular than ever.
00:08:42Even so, it's thought nine out of every ten caves are yet to be discovered.
00:08:48These are the new frontiers in the exploration of our planet.
00:08:53But these days, we know we can't get to the center of the Earth this way.
00:08:57The deepest caves go down only 5,000 feet.
00:09:02But need, and some would say greed, have driven us to penetrate much further into our planet.
00:09:11Early mining started as simple holes in the ground,
00:09:14but as the surface deposits have been used up,
00:09:17we've had to go deeper, digging shafts and tunnels.
00:09:25And if the prize is big enough, it's worth going a long way down.
00:09:34These men are plummeting towards the center of the Earth.
00:09:40They are in search of gold, a metal valuable enough to dig two miles down to get it out.
00:09:48The mine is so deep that the cable would break under its own weight if it was continuous.
00:09:54That's why the miners have to change cages halfway.
00:10:07They're already 2,000 feet below the bottom of the deepest mines Verne knew about.
00:10:15Today, this is the deepest mine on Earth.
00:10:19It's also the deepest anyone has been into the Earth's crust,
00:10:23and these miners do it every day going to work.
00:10:28They're 12,000 feet down.
00:10:36There's a way of going still deeper that doesn't involve digging, but it does require diving.
00:10:47The deepest place on Earth is at the bottom of the ocean.
00:10:52In 1960, a submersible called Trieste got there,
00:10:56a century behind Nautilus, the submarine in Verne's book 20,000 Leagues Under the Sea.
00:11:05Apart from Nautilus' crew, the two men aboard the Trieste are the only people to penetrate this far into the abyss.
00:11:15More men have walked on the moon.
00:11:18Here, the ocean is deeper than our highest mountains.
00:11:23The Trieste dived as far from its surface as the airliners cruising overhead, seven and a half miles.
00:11:37We can get deeper than that by drilling.
00:11:42This is the site of the bid to drill the deepest hole on Earth.
00:11:47In Verne's day, drilling for water was routine, down to around 100 feet.
00:11:54But five years before Journey, drills were used to find oil.
00:12:02The technology went into overdrive, but even a century later,
00:12:06the Russian goal of 40,000 feet looked like a step too far.
00:12:15The German attempt had failed at 30,000 feet because the rock was so hot and soft, it sealed the hole.
00:12:23After 14 years, the Russians made it.
00:12:27Core samples were eagerly analyzed by geologists.
00:12:31No one had ever seen rocks from this far down.
00:12:35So how near have we got to the center of the Earth?
00:12:41Cavers venture 5,000 feet down, while miners work at 12,000 feet.
00:12:50And the Trieste plunged to 34,000.
00:12:54Up to now, we've drilled to 40,000.
00:12:58But it's 21 million feet to the center of the Earth.
00:13:04We've barely scratched the surface.
00:13:11Why does this man keep scrambling and squeezing his way down?
00:13:18He's in search of something more precious than gold.
00:13:29Jules Verne lived at a boom time for science.
00:13:33When the natural world took center stage.
00:13:37He trained as a lawyer, not a scientist, but started to devour scientific papers as a student
00:13:43and kept up with new discoveries all his life.
00:13:47Always hungry for material, Verne picked the brains of many top scientists.
00:13:54Charles Sinclair Davy, a world expert on volcanoes, provided inspiration for Journey.
00:14:04In the middle of the 19th century, the big questions about the Earth were still to be answered.
00:14:10How old was it? How was it made?
00:14:14For many people, the answers were a matter of faith.
00:14:18The problem was, science was suggesting that may not be true.
00:14:25Darwin had just published his theory of evolution.
00:14:29The world and all living things weren't made in 6,000 years, but millions.
00:14:35Knowing about fossils had prepared Verne for that.
00:14:38But fossils embarrassed the faithful.
00:14:41How could their god let his creations go extinct?
00:14:46When mammoth fossils were found in America,
00:14:49even Thomas Jefferson believed they must still be alive there.
00:14:54It was just too good an opportunity for Verne to miss.
00:15:05In his novel, Verne conjured up a scene in which the professor, Axel, and Hans would find more than old bones.
00:15:16What if they found hundreds of miles below the surface, ancient species living on?
00:15:46What if they found hundreds of miles below the surface, ancient species living on?
00:15:52What if they found hundreds of miles below the surface, ancient species living on?
00:15:59What if they found hundreds of miles below the surface, ancient species living on?
00:16:06What if they found hundreds of miles below the surface, ancient species living on?
00:16:14What if they found hundreds of miles below the surface, ancient species living on?
00:16:20We're still finding fossils all over the world.
00:16:27We have better tools than the hammers and chisels Verne would have recognized,
00:16:32but freeing the precious bones from the rock is still a painstaking task, requiring skill and patience.
00:16:40Fossils are the remains of plants and animals that once lived.
00:16:43So, for example, if you have a creature that lives in the sea, when it dies its carcass would fall to the bottom,
00:16:48and over time the bones would be picked clear of flesh by any scavengers down there,
00:16:53and then it would eventually be buried presumably by sand or silt,
00:16:56and then in the course of maybe tens or hundreds of years, with pressure of more sediment on top,
00:17:01the bone is infiltrated with minerals, and there you have a fossil.
00:17:05In Verne's day, enthusiasm often got the better of expertise.
00:17:10Bones of different species might be assembled to make animals that never walked the earth.
00:17:15Things are very different today.
00:17:18So the paleontologist is a detective who looks at these bits and pieces of ancient plants and animals,
00:17:24puts them together using anatomical knowledge, comparisons with modern forms,
00:17:28and you can literally bring the past back to life.
00:17:32This may be the oldest plant-eating dinosaur yet found.
00:17:36It lived on tropical islands like those in the Caribbean.
00:17:40So why, Verne would have asked, was this one found in Britain, where it's cold and damp?
00:17:46Because 200 million years ago, Britain was way down south, near where North Africa is today.
00:17:55And the sea level was so much higher, the hills of Britain were islands.
00:18:02By Jules Verne's time, people understood a little bit about the history of the earth.
00:18:05Geologists had been studying the sequence of rocks for about 30 years or so.
00:18:10And they realized as you go back in time, you got into more and more ancient rocks,
00:18:14and as you looked at the fossils, you got more and more unusual and ancient-looking creatures.
00:18:23In his book, Verne was able to bring the past back to life
00:18:28and adapt species of the present to life underground.
00:18:35He knew that plants couldn't survive there since they need sunlight,
00:18:39but figured that fungi could thrive.
00:18:46In the higher temperature and humidity deep down,
00:18:49he had his heroes encounter mushrooms of awesome proportions.
00:19:29But what can really be found on a journey to the center of the earth?
00:19:40Bats may be the best-known cave dwellers,
00:19:43but they only use caves as hotels, going out at night to feed.
00:19:48You have to go deeper to find a stranger life.
00:19:52Apart from the oceans, no other habitat is so alien to our experience.
00:19:59Most of the animals that live here came from the surface,
00:20:02perhaps fleeing changes in landscape or climate.
00:20:06Over thousands of years, they've adapted to this dark world.
00:20:12They need no coloration to survive,
00:20:15but they can adapt to any environment.
00:20:19They need no coloration to protect them from the sun,
00:20:23and no eyes to see since they live in total darkness,
00:20:27finding their food by touch and smell.
00:20:30Cave-dwelling animals known as troglodytes are difficult to study.
00:20:35They live in such tiny crevices they may never be found,
00:20:40even by the most intrepid explorers.
00:20:43But it's other creatures down here that are exciting scientists today,
00:20:48creatures so small you can't see them with the naked eye.
00:20:53And to work with these elusive life forms,
00:20:57John Parks faces a commute that most people would do anything to avoid.
00:21:04We do find life in the earth,
00:21:07despite the fact that the deeper you go,
00:21:10the higher the pressures and the higher the temperature.
00:21:12But life is very small.
00:21:15It's microscopic organisms, mainly bacteria.
00:21:18And these organisms can survive those conditions.
00:21:21In fact, some can grow at temperatures as high as 113 degrees centigrade,
00:21:27much higher temperatures than boiling water.
00:21:33The startling thing about life in the subsurface
00:21:36is the first estimates of the total bacterial population there
00:21:41indicate that they represent about 70% of all bacteria on earth.
00:21:48So the majority of bacteria actually reside in the subsurface.
00:21:52They're not in this thin veneer very close to plants and animals we're used to.
00:21:58But what do bacteria find to eat down there?
00:22:02New discoveries suggest it may be the earth itself.
00:22:08In Verne's day, science believed that all caves were created by water,
00:22:14wearing away the rock.
00:22:16But is this right?
00:22:19These caves were formed millions of years ago,
00:22:23before the sea level rose.
00:22:25Now they're only open to intrepid diver scientists like Sam Smith.
00:22:31She believes it's not water that eats away the rock.
00:22:35It's bacteria.
00:22:37I think that without bacteria, caves and limestones would not exist.
00:22:43You really do need the bacteria to form carbonic acids or other acids
00:22:49in the soil zone above where the caves might start to form or develop,
00:22:53which then starts to carve out the cave.
00:22:56There's no doubt that over time, water corrosion also plays a role.
00:23:03But bacteria need to be there as well.
00:23:07Microbes or meteors?
00:23:10Join our teams of scientists as we go deeper still,
00:23:14searching for clues about what formed the earth.
00:23:22Sam's study site is in the Yucatan Peninsula in Mexico.
00:23:28The caves extend for 50 miles and are up to 400 feet deep.
00:23:37If Sam is right, rock-eating bacteria hollowed them out and they're still at it.
00:23:44The quest for the bacteria takes her deep into the underwater maze.
00:23:58This is a dangerous place.
00:24:01Sam's exploration is at the limit of diving technology.
00:24:06There are only three scientists in the world experienced enough to dive into caves this deep.
00:24:14All their equipment has a backup, or even two, since problems must be solved on the spot.
00:24:23This is no place to get lost with your air running out.
00:24:43When Sam finally gets to a spot where the rock-eating bacteria could be at work,
00:24:48she makes sure the samples she collects will be perfect.
00:24:53To take our samples, we use 10-meter length tubing, silicone tubing,
00:24:59that basically allows us to take a sample at a point 10 meters upstream of us
00:25:04and it minimizes the diver's disturbance to the water,
00:25:07so that sample is as sterile and as clean as possible.
00:25:12Having come this far, it's vital that Sam doesn't contaminate the samples with her own bacteria.
00:25:19Only then can the return journey begin.
00:25:23After we've collected the samples, we immediately take them back to the cave surface
00:25:27where they are put on ice right away and kept on ice until we get them back to the field lab.
00:25:42The bugs are cooled to 40 degrees and flown in this standby state from Mexico to Sam's lab in England.
00:25:50It takes about eight hours.
00:25:53A Jules Verne hero managed to race around the world in 80 days.
00:25:58It was 10 years after Verne wrote Journey that Louis Pasteur put bacteria on the map.
00:26:06And for another century, the world would see bacteria as a nuisance.
00:26:11Now scientists like Sam suspect they may become a vital and inexhaustible commodity.
00:26:18First, she wants to know how many rock-eating bacteria there are.
00:26:24She wants to know if they're all the same type.
00:26:28Most of all, she wants to verify that the acids they produce can carve out caves.
00:26:34If Sam's right about these microscopic miners, it's a giant step forward for geology.
00:26:45It's something that's quite exciting to think that something so small,
00:26:49so the bacteria which are about a micron in size, so one millionth of a meter,
00:26:55can actually alter something so large and have such a large impact on the environment around them.
00:27:07Bacteria exist everywhere in the air, in water, land, sea.
00:27:12And anywhere we've looked for them so far, we've been successful at finding them.
00:27:17So will we find bacteria at the center of the Earth?
00:27:22If you want to think about how deep we could go and still find bacteria,
00:27:26it probably is temperature dependent, but we haven't reached that maximum yet.
00:27:31We haven't looked deep enough yet where they haven't been there.
00:27:37Because they can eat what we can't eat and thrive in conditions we find extreme,
00:27:43bacteria may turn out to be the Earth's real buried treasure.
00:27:47They're already at work in our homes.
00:27:50We all are used to using biological detergents in washing powders.
00:27:56These come from organisms that can grow at 60 degrees centigrade.
00:28:00If we can get organisms growing at 130, 150 degrees centigrade,
00:28:05basically they could make superb catalysts for a whole range of different compounds.
00:28:11Unlike some other resources, there's a lot more.
00:28:15Unlike some other resources, there's no shortage of bacteria.
00:28:19This core sample of rock comes from 200 feet below the surface.
00:28:24It contains as many bacteria as there are people on this planet.
00:28:30We've come up with bacteria wherever we've drilled and however deep.
00:28:36They can survive for millions of years, buried alive, without food or oxygen.
00:28:43Some see them as an infinite, untapped labor force.
00:28:47The first oil wells came online in Vern's time.
00:28:51But the era of easy-to-get-at fossil fuels is almost at an end.
00:28:56Unless these new microbial workers can help us out.
00:29:01We know that we leave something like 40% of all the oil in reservoirs in the ground.
00:29:07We can't extract it.
00:29:09And, for example, if we're able to manipulate these deep organisms,
00:29:12they might be able to convert the oil into gas,
00:29:15and then several years later we could come back and we've got a viable gas field,
00:29:21instead of a spent oil field.
00:29:25Vern's adventurers didn't strike oil, but they did find platinum and gold.
00:29:31They decided these were too deep ever to be mined.
00:29:35Vern meant by men. He hadn't reckoned on microbial miners.
00:29:40The idea of using microbes to extract minerals was beyond even Jules Vern's imagination.
00:29:47But because some types of bacteria digest rock,
00:29:50they're already being used to separate metals from ore.
00:29:55And that's just the beginning.
00:29:58One day, we'll be able to put bacteria to work at depths we just can't tolerate.
00:30:06Until then, we'll go on doing it the hard way.
00:30:11Mining at 12,000 feet is difficult, dangerous, and expensive.
00:30:17Every mile you descend, the earth gets hotter by 50 degrees.
00:30:25Here, a single bacterium can live for 1,000 years on a diet of nothing but rocks.
00:30:31Bacteria living here are natural alchemists.
00:30:35They play an integral role in creating deposits of gold.
00:30:39As they break down the rock and mineral ores,
00:30:42the bacteria attract molecules of gold to their outer skin.
00:30:49Over millions of years, the gold builds up to form a glittering gold deposit.
00:30:59The mine uses more electricity than a small city,
00:31:03making 80,000 tons of ice a day
00:31:07and lifting 10 tons of ore two miles to extract each and every ounce of gold.
00:31:17It's the rock's history that lets us mine here this deep.
00:31:21Most places would be simply too hot.
00:31:24But in South Africa, the earth's crust is older than in most other places,
00:31:29so it's had more time to cool.
00:31:33Two and a half billion years ago, the gold accumulated on the surface in a lake.
00:31:39Over time, the land and the gold was tilted and forced down into the earth.
00:31:45No richer deposit has been discovered.
00:31:55Three quarters of the world's gold has come from it,
00:31:58but that's only 2,000 tons.
00:32:02To find out why metals like gold and platinum are so rare,
00:32:06we must go back to a time when the whole of the earth was molten.
00:32:174.6 billion years ago, a continual rain of meteorites pounded the molten earth.
00:32:27Each strike brought with it more rock, making our planet bigger
00:32:32and scattering metals over the surface.
00:32:41Then a giant asteroid struck.
00:32:52Its massive iron core didn't stop on the surface.
00:32:56It sank towards the center,
00:32:59and it attracted all the earth's metals to it as it went.
00:33:09The asteroid's lighter, rocky debris went spinning around the earth.
00:33:15The fragments were drawn together by gravity.
00:33:20Within a year, they formed our moon.
00:33:31That's why the moon has no metal at its core.
00:33:37And it's why metal is rare in the earth's crust.
00:33:41It arrived much later, in meteorites from outer space.
00:33:47If we want much more metal, we must go to the earth's core.
00:33:52It's made mostly of iron and nickel, but 1% is gold.
00:33:58That may not sound like much, but the core is so vast
00:34:02that its gold could cover all the land on earth, knee-deep.
00:34:12In South Africa, the miners are already going deeper in search of more gold.
00:34:22They plan to follow the seam to three miles down,
00:34:26where keeping the mine cool could account for 20% of the mine's outlay.
00:34:33They may need temperature-controlled suits or robots to extract the precious metal.
00:34:42The northern and southern lights, beautiful and benign.
00:34:48But what will happen when the lights go out?
00:34:58In 1860, no one really had a clue what went on 4,000 miles below their feet.
00:35:06Many people still believed that the earth was hollow,
00:35:09a theory put forward 200 years before by the astronomer Halley of comet fame.
00:35:21In 1823, an American, John Cleves Sims, had led an expedition to prove that Halley was right.
00:35:30He didn't succeed.
00:35:35Jules Verne knew of Sims' theory and kept an open mind.
00:35:42But he led his explorers into an immense underground cavern,
00:35:47in which they had to cross an ocean lit by lightning and magnetic storms.
00:35:56This was pure fantasy.
00:35:59But the scene also drew on fact.
00:36:03Verne's research had convinced him that traveling down into the earth would be like going back in time.
00:36:15The creatures stirring in the deep were real.
00:36:20200 million years ago.
00:36:27Plesiosaur.
00:36:29The first remains of the long-necked reptile were found in 1820.
00:36:36A coffin-shaped ichthyosaur, unearthed in 1809.
00:36:53Verne was right. There is an ocean at the center of the earth.
00:37:00A tempestuous sea of molten iron.
00:37:06As this surges in turmoil around the solid inner core, it generates magnetism.
00:37:14A colossal force field stretches into space, protecting us from solar radiation.
00:37:24Sometimes we can see it.
00:37:30The northern and southern lights put on a show when electrically charged fragments from the sun collide with the magnetic field.
00:37:39But there's evidence that its power is fading.
00:37:44And that could mean we'll be exposed to a lethal dose of cosmic rays.
00:37:50At Harvard, Jeremy Bloxham is trying to find out why this is happening.
00:37:56One of the goals of our research at the moment is to try to develop a capacity to forecast what's going to happen to the magnetic field in the future.
00:38:06And this is of particular interest at the moment because over the last 150 years, we've seen the strength of the field decrease by almost 10 percent.
00:38:16And that's a rate of decrease which is characteristic of the field heading into a magnetic reversal.
00:38:23So an interesting question is, will the magnetic field actually reverse?
00:38:28A magnetic reversal, or flip, means the North Pole becoming the South, and vice versa.
00:38:35Compasses will point the wrong way. Navigation will be literally turned upside down.
00:38:43But this won't be the first time it's happened.
00:38:48There's been maybe 60 reversals in the last 30 or 40 million years.
00:38:54So in geological terms, they're a very frequent event.
00:38:58Just in the timescale of human experience, they're a very rare event.
00:39:05But what will happen in a flip?
00:39:10Will we be able to find our way around?
00:39:13Today, magnetic compasses are used less for navigation.
00:39:17Instead, we use GPS satellites, which won't be affected.
00:39:23But before the flip, the Earth's magnetic shield will fail.
00:39:27And without it, satellites, bombarded by radiation, will burn up in space.
00:39:34It's not only human navigation that will go wrong.
00:39:38Many animals rely on internal magnetic compasses for migration.
00:39:45But no one knows how they will manage.
00:39:49But flips don't happen overnight. The force field fades slowly.
00:39:54Jeremy Bloxham is watching it closely.
00:39:58There's a variety of techniques which we can use to see how the field is changing.
00:40:03We have modern measurements from spacecraft, which are in orbit,
00:40:08specifically to measure the magnetic field.
00:40:11We have permanent magnetic observatories set up at various locations around the world,
00:40:17which continuously make measurements of the magnetic field.
00:40:21But measurements like that only tell us what's happening on a timescale of decades
00:40:26to perhaps a century for the longest-running observatories.
00:40:30The magnetic field is changing on much longer timescales,
00:40:33so we need to be able to ask, how can we find out how the field has changed over centuries?
00:40:44Fortunately, navigators long depended on the magnetic field,
00:40:48and we've learned a lot about its variations from their charts.
00:40:54And the changes continue.
00:40:57Today, Magnetic North is leaving Canada and heading across the Arctic Ocean at a steady 10 miles a year.
00:41:07But it's one thing to know the poles are moving, another to know why.
00:41:13The Earth's core is liquid iron, or mostly liquid iron,
00:41:17and the motions of that electrically conducting iron can create what we call a dynamo.
00:41:24But the details of that process, how it actually works, are still very poorly understood.
00:41:30To understand it better, Dan Lathrop has built a working model of the Earth's core.
00:41:37We've been building a sequence of experiments, progressively larger and higher powers,
00:41:43to try to get the same parameters as occur in the Earth's outer core
00:41:48and try to understand how the Earth generates its magnetic field.
00:41:55Keep an eye on the temperature, too.
00:42:02We like to know what sets how strong the Earth's magnetic field is.
00:42:08We also would really like to understand what causes all the changes that are seen,
00:42:14anomalies in the field and reversals,
00:42:16and to be able to both understand what causes them and be able to predict them.
00:42:22The floor of the Atlantic Ocean bears witness to flips of the past,
00:42:26because lava lines up with the magnetic field as it solidifies.
00:42:31The problem is, flips aren't regular.
00:42:35To predict the next one, we must know what's going on in the core.
00:42:44We have two different types of experiments that we're currently working on.
00:42:49In the first experiment, we actually drive propellers that churn the fluid,
00:42:54propeller on either side, that sets up this sort of wildly turbulent flow.
00:43:00Okay, getting ready to run at 10 RPS.
00:43:04At the heart of Dan Lathrop's dynamo is a sphere filled with hot sodium.
00:43:10Electrically, sodium behaves like molten iron, but it's 1,000 degrees cooler.
00:43:18A propeller creates the sort of turbulence thought to be caused by the rotation of the Earth.
00:43:25Up to now, they haven't been able to generate a steady amount of magnetism.
00:43:30But they have learned that small changes in speed and temperature
00:43:34significantly affect the magnetic field.
00:43:40In the other experiment, we have a geometry very close to the Earth's outer core,
00:43:45where we rapidly rotate a sphere which has a layer of liquid metal,
00:43:50and then we heat the outer edge and cool the inner sphere,
00:43:53and set up convection, sort of like you might have boiling in a pot and making pasta.
00:43:57In this case, it's sort of the churning of the liquid metal
00:44:00that gives rise to a turbulent flow that affects the magnetic field.
00:44:05The next step is to build a bigger model.
00:44:08After all, the real Earth's core is over 4,000 miles in diameter.
00:44:15There are really three main questions that we're trying to understand in the experiments.
00:44:20We'd like to know what sets how strong the Earth's magnetic field is.
00:44:27We also would really like to understand what causes them and be able to predict them.
00:44:32And the last thing is we'd like to know what are the limits to having a dynamo on a planet.
00:44:38So why does the Earth have a dynamo and Venus does not?
00:44:42Einstein insisted the question of how the Earth generates so much magnetism
00:44:47was the most important unsolved puzzle of physics.
00:44:51No one knows when the next reversal will happen.
00:44:54One thing is certain, though.
00:44:56The magnetic poles will reverse.
00:45:02Scientists in Verne's day knew that magnetism came from within the Earth,
00:45:07but not about magnetic reversals.
00:45:10Yet he predicted a magnetic flip.
00:45:18His explorers had been traveling for months.
00:45:21Professor Lidenbrock reckoned they were almost at the center of the Earth.
00:45:28They stopped to draw breath and take a bearing.
00:45:35That's when they realized something was wrong.
00:45:40Their compass had gone crazy.
00:45:44Had Verne seen into the future again?
00:45:49He certainly knew of the connection between magnetism and electricity
00:45:53because he tells us that the compass flip occurred during the storm at sea,
00:45:57when lightning struck the boat.
00:46:06Don't try this at home.
00:46:08Fortunately, this isn't the only way to find out when the volcano's going to blow.
00:46:19Volcanoes are the richest source of rock from deep inside the Earth.
00:46:24The most active is in Hawaii.
00:46:29This is the closest we can get to what it's like at the center of the Earth.
00:46:35It's a reminder of the heat and power hidden beneath the surface of our planet.
00:46:44Kilauea volcano has been spewing out lava for thousands of years without a let-up.
00:46:50It single-handedly built the island.
00:46:55Molten rock, called magma, surges up from near the Earth's core and blazes through the crust.
00:47:02The stream, known as a plume, lets inner Earth let off steam.
00:47:07It's like a safety valve.
00:47:10We believe that the volcanism at Hawaii is ultimately caused by a hot plume rising up beneath it,
00:47:18which occurs because material at the bottom of the mantle is heated up by the core.
00:47:23The core's maybe 2,000 degrees C hotter.
00:47:26And heating it up causes it to become less dense, and then it rises through the mantle.
00:47:34A good analogy is with a lava lamp that you might see in someone's living room.
00:47:42It's lamps like this that show us what's going on in the Earth's mantle,
00:47:46the layer between the core and the crust.
00:47:50The rock heated by the core rises while cooler material sinks from the surface.
00:47:57It's this never-ending process known as convection that pushes magma to the surface, where it erupts as lava.
00:48:11Hawaii is a bit of a special example. It's the most active island volcano that there is.
00:48:17It erupts with extreme frequency, and it's also exceptionally runny, and so the lava flows tend to move very fast.
00:48:25And they have a high proportion of these so-called pahoehoe surfaces,
00:48:29which are these beautiful, smooth, ropey textures that you see.
00:48:35Lava can build, but it can also destroy.
00:48:39It can seldom be diverted, and it wipes out anything and anyone that gets in its way.
00:48:53Early geologists assumed that such torrents of molten rock flowing out of volcanoes must leave huge voids and caverns behind them.
00:49:02Jules Verne's explorers followed one of these lava tubes as they approached the center of the Earth.
00:49:10But the Earth had one last surprise in store for them.
00:49:18As the professor asked the students to find out what was in the lava,
00:49:23they were told that the lava was a mixture of sulfur and sulfuric acid.
00:49:29As the professor, Axel, and Hans neared the center, their path was blocked by a rockfall.
00:49:39There was no other route, so they decided to blast their way through.
00:49:59Verne knew very well that molten rock trapped deep in the Earth is under huge pressure.
00:50:09If that pressure is released, it can start a volcano.
00:50:14That's why blasting was a risk.
00:50:19The lava was so thick that it could be blown into the atmosphere.
00:50:24was a risk.
00:50:54In classic literary tradition, the eruption they triggered blasted our heroes to the
00:50:59surface without as much as a singed eyelash.
00:51:05Eruptions are how the earth recycles itself.
00:51:08Convection currents in the mantle carry rock to volcanic vents and fire it back to the
00:51:13surface.
00:51:16Volcanologists today can't get inside an active volcano, but they get up close.
00:51:22Tim Elliott plays his part 8,000 miles away.
00:51:26As geochemists, we tend to come in after the thing's cooled down and then knock bits off.
00:51:33Predicting eruptions is every volcanologist's aim, but it makes predicting the weather look
00:51:38easy.
00:51:41Lava samples tell us that the earth's composition is complex, and it changes whenever a large
00:51:48earthquake or eruption occurs.
00:51:52For Tim Elliott, who struggles to keep tabs on this shifting underground world, every
00:51:58sample is a rich source of information.
00:52:06For what will eventually be a highly sophisticated piece of analysis, Tim starts by crushing
00:52:12the lava in a machine Jules Verne might well have designed himself.
00:52:20The first thing is to break the lava into pieces.
00:52:25Then it must be crushed into a fine powder.
00:52:36The next step must be done with great care.
00:52:41The hydrofluoric acid Tim uses to dissolve the powder is equally good at dissolving skin
00:52:47and bone.
00:52:51It eats all the rocky parts away, leaving just the base elements.
00:52:57Those are the parts Tim's interested in.
00:53:03The lava sample is heated and the acid evaporated off overnight.
00:53:10Once we've got a pure separate of the element that we want, we then take that to the mass
00:53:14spectrometer to analyze its isotope ratio.
00:53:23Wherever they come from, any two samples of a chemical element will be chemically identical.
00:53:33But we now know that they can differ physically.
00:53:39A mass spectrometer can tell them apart and tell Tim just where in the earth a sample
00:53:46came from.
00:53:48This one came from very deep indeed.
00:53:53So that maybe gives us a clue that these things come all the way from the core mantle boundary.
00:53:59But in terms of the ultimate depth of these things, to some extent, I hate to admit it,
00:54:03but I rely on the seismologists.
00:54:1010, 9, 8, 7, 6, 5, 4, 3, 2, 1.
00:54:29Seismologists can see inside the earth without going there.
00:54:33Their explosions create shockwaves of sound.
00:54:38When the waves hit rock, they bounce back to sensors on the surface.
00:54:47Since different rocks reflect waves at different speeds, seismology lets us map the earth's
00:54:52subsurface landscapes.
00:55:01Can today's technology take us to the center of the earth?
00:55:06If so, what would we find there?
00:55:19Seismology lets us see with sound.
00:55:22And there's more to it than creating big bangs, as MIT's Rob van der Hilst explains.
00:55:30Seismology is pretty much the only way to get fairly direct probes of the earth's interior.
00:55:35And there's a lot of development in the seismic theory and observational seismology itself
00:55:40to really give much more refined images.
00:55:46Seismology is similar to an ultrasound scan that can show an unborn baby in its mother's
00:55:51womb.
00:55:53An image can be created because sound travels through different parts of our body at different
00:55:58speeds.
00:56:00Unlike this scanner, which generates its own sound, seismology can make use of natural
00:56:06sounds that occur every minute or two.
00:56:11The sound of earthquakes.
00:56:13Thankfully, we don't notice most of them, but there are actually a million a year.
00:56:19And they're shaking up our ideas about what's going on thousands of miles beneath our feet.
00:56:29Earthquakes are appallingly destructive to human life, but to scientists, they have their
00:56:34uses.
00:56:35The seismic waves are like sonar.
00:56:38By listening as they pass through the earth, a picture can be built up of a place no one
00:56:43can ever see.
00:56:45First, the waves race through the crust, the skin on the planet's surface.
00:56:51In some places, only four miles separates us from the intolerable heat of the magma
00:56:57in the interior of the earth.
00:56:59The temperature is nearly 3,000 degrees, so intense that the rocks are partially melted.
00:57:073,000 miles down in the core itself, the temperature reaches an unimaginable 7,000
00:57:14degrees.
00:57:15It is the ultimate nuclear reactor, the engine driving the planet.
00:57:22What we can really image very well is the material that goes down.
00:57:25And in some cases, we can see down to the core metal boundary.
00:57:28And all that information tells us a little bit about, you know, how density is concentrated
00:57:32in the center of the earth and how density changes with increasing depth.
00:57:39Seismologists image rocks.
00:57:42Petrologists make them, mimicking the heat and pressure of the deep earth.
00:57:52Now we know where they come from, we know how deep they come from, because the minerals
00:57:57contain elements like calcium and aluminum.
00:58:01And the distribution of these elements between the different minerals depends on pressure.
00:58:08So by simulating the pressure, taking a sample like this and subjecting it to high pressure
00:58:14and seeing how the compositions of the minerals change as we change the pressure, we can go
00:58:19back and work out what depth this particular sample came from.
00:58:26The anvil on which Bernie forges his man-made minerals is made of tungsten carbide, a material
00:58:32so hard we use it to make drills.
00:58:36He puts a tiny sample of rock in a ceramic tube, a miniature furnace, and then walls
00:58:42it up.
00:58:45The bricks are specially shaped to focus the force he'll apply to them.
00:58:53This way, he aims to reproduce the massive pressures to be found in the earth.
00:59:00Over a period of about four or five hours, we raise the force to around 500 tons, and
00:59:06we then apply a current to the furnace, which is in the middle of that lot, in order to
00:59:11raise the temperature to 1,700 degrees C.
00:59:17The petrologist awaits the outcome as anxiously as a pizza chef.
00:59:23If the heat and pressure are right, the elements will fuse together into an exact copy of the
00:59:29mineral he's studying.
00:59:32This tells him where it came from, in this case, 440 miles down, where the pressure is
00:59:39a quarter of a million times higher than at the surface.
00:59:46The advances in science since Verne's time have been breathtaking, and we're still discovering
00:59:55how the earth was made, and how it continues to change.
01:00:00We've come a long way, not in distance, but in knowledge.
01:00:04We've ventured 200,000 miles into space, but as yet, we've only been seven miles into
01:00:11our own planet.
01:00:16With all the knowledge and technology we have today, surely we can tunnel to the center
01:00:21of the earth.
01:00:29If we could tunnel to the core, the rewards would be huge.
01:00:38We could shut down our power stations. The energy we'd tap into would never run out.
01:00:46It would be free, and cause no emissions.
01:00:51We could dispose of dangerous waste in the world's hottest incinerator.
01:00:59Huge quantities of minerals are there, just waiting to be brought to the surface.
01:01:08Maybe we could build a high-speed transportation system through the earth, a global subway.
01:01:18But it's not that easy.
01:01:22This tunnel, linking England and France, took five years to construct, and it's only thirty
01:01:27miles long.
01:01:32It's 4,000 miles to the center of the earth.
01:01:38And would we actually want to go there?
01:01:42It's an adventure that Dan Lathrop would welcome.
01:01:45It's an interesting idea for an adventure. I guess I'm ready to go, if it becomes possible.
01:01:53Meet the team that's designing the first vehicle capable of penetrating to the center
01:02:02of the earth.
01:02:10Today's tunneling machines have brains as well as brawn.
01:02:14They drill and support the tunnel as they go, and never stop.
01:02:20But what chance has even a smart monster like this of getting to the center of the earth?
01:02:26Brian Clark has built tunnels all over the world.
01:02:30If we're tunneling to the center of the earth, there are different combinations of material,
01:02:36but generally we would start in soft ground tunneling.
01:02:41We would move through into rock, and as we go to extreme depth, the rock would change
01:02:48in character due to the temperature effects.
01:02:57We almost certainly would need to use an arm with a cutter head, tungsten carbide teeth
01:03:03on it, to grind and smash the rock.
01:03:06Today's most advanced mechanical moles can dig two feet every hour. At that rate, tunneling
01:03:1324 hours a day, it would take a thousand years to reach the center.
01:03:20We'd have to make them work faster, much faster.
01:03:28And if you think of the tunneling machine as a very large beer can, and it's traveling
01:03:46end on end, down through the earth, with cutters up front, the closed face, it means that the
01:03:53cutters, cutting away at the soft ground, are separated by a wall from the men on the
01:04:03inside, and all of the spoil, all of the earth that's being cut, is carried to the surface
01:04:10in pipes.
01:04:23The amount of rock and spoil coming out of the tunnel is almost unimaginable.
01:04:33We'd need to extract four giant truckloads of earth per hour, 100 per day, 36 million
01:04:40truckloads in all. And that's if we tunneled straight down, not on a grade.
01:04:48We'd have to design a new type of vehicle to transport us through the tunnel, maybe
01:04:55a capsule able to withstand the extremes found deep inside the earth.
01:05:02The deeper we go, for every kilometer in depth, we're picking up a 30 degree centigrade temperature
01:05:08rise, and that is causing us problems. The rock is getting softer, it's getting ductile
01:05:15as a result of the higher temperatures. We're having to resist those temperatures so that
01:05:19people can work within the tunneling machine, or we would need to produce a remote machine.
01:05:25I think we're now stretching credibility.
01:05:28But it's not only temperature that will be a problem. There's also massive pressure down
01:05:33there.
01:05:34I would say it would be incredibly difficult. I think in comparison the environment as you
01:05:41go deeper into the center of the earth is much more harsh than what you would find,
01:05:46for the most part, for space travel, with the temperatures and the pressures you'd find.
01:05:52It's actually a much more hostile environment than going in space or down in the ocean.
01:05:59And in particular, high pressures are such that we wouldn't know how to make a vessel
01:06:04that you could go inside and not get crushed down, down, you know, really past a few miles
01:06:11the pressures would start to get too high for any sort of normal technology.
01:06:22We already know a thing or two about building complex vehicles. Could we spin off space
01:06:29technology to help get us to the center of the earth?
01:06:36Clearly one of the biggest issues you're going to have with a trip like that is going to
01:06:38be the extreme temperatures and pressures. Some of the best materials that we have currently
01:06:45for dealing with temperatures like that would be the ceramic tiles in the shuttle or some
01:06:49kind of carbon-carbon or any type of carbon-based material.
01:06:55But here's the hitch. While man-made materials like ceramics and carbons withstand heat,
01:07:02they lack strength. Metal is strong, but most steel melts at around 2,500 degrees. The temperature
01:07:10at the earth's core is probably 14,000. We need new materials to build our capsule or
01:07:17to shield it.
01:07:19Sometimes if time is on your side and you're not going to be exposed to the temperature
01:07:23for very long, simply having a material with enough heat capacity to absorb the heat that's
01:07:28flowing into the system without melting would be sufficient.
01:07:35The best bet that I know of as far as temperature is diamond. And even diamond I think has a
01:07:41melting temperature of 3,200 Kelvin. So from a material standpoint, I don't know of any
01:07:46materials on their own that would be able to withstand those temperatures.
01:07:52As well as being the ultimate adornment, diamond is the hardest substance known. We
01:07:58can manufacture diamonds, but could we make one big enough from which to build a capsule?
01:08:04Well, the diamond certainly would be the strongest material and would allow you to have the highest
01:08:11pressures. It's not entirely clear you, of course, can fabricate an entire vessel.
01:08:19A tunneling machine using conventional technology would be destroyed by heat and pressure long
01:08:26before it reached the earth's center. Only 20 miles into its 4,000 mile journey, it would melt.
01:08:39But if one day we could conquer these technical problems, there may be a way we could send
01:08:45a capsule deep into the planet. We'd have to harness the most powerful force on earth,
01:08:53continental drift.
01:08:58The theory of continental drift, also called plate tectonics, was finally accepted by science
01:09:04in the 1960s, a century after Jules Verne's day. It's said that the land masses we're
01:09:12familiar with started out as one supercontinent. This sat on plates that migrated across the
01:09:22globe. But the plates haven't stopped. In another 20 million years, our world will look
01:09:31very different.
01:09:42This is the San Andreas Fault.
01:09:53These two plates are sliding past each other at the same speed your fingernails grow. Most
01:10:02of the time, these plates slide smoothly, but occasionally they get stuck. And this
01:10:11causes earthquakes. Plates don't always slide past each other. In some places, one plate
01:10:29is forced beneath the other. That's what's happening underneath Japan.
01:10:37It looks serene, but beneath the surface, it's a different story. The Pacific Plate
01:10:50and Asia are colliding head on. Below the picturesque landscape, the Pacific Plate is
01:10:58being driven under Asia, a process called subduction.
01:11:06It makes Japan a hotspot, not just for volcanoes, but for earthquakes as well.
01:11:17Japan's volcanoes look genteel, but don't believe it. It's feared they'll destroy the
01:11:25islands they once created. If we could take our capsule deep below Japan, we'd find that
01:11:33the volcanoes aren't like the ones we saw in Hawaii.
01:11:39At Kilauea, the heat and pressure of the deep earth blast out streams and fountains of molten
01:11:46lava. Under Japan, there's a different driving force beneath volcanoes, subduction.
01:11:55As subduction buckles and breaks the earth's crust, seawater flows in. Hot rock and cold
01:12:02water are an explosive mixture. Subduction triggers earthquakes too. Tetsuro Urabe is
01:12:14a professor at the University of Tokyo. Eight years ago, a quake killed 6,000 people, including
01:12:23his mother. He now works on earthquake prediction.
01:12:32The Japanese Island Arc is located in the western rim of the Eurasian continent, where
01:12:38the plate of the Pacific Ocean floor goes down beneath the island arc. So that kind
01:12:45of active setting makes all those natural disasters like volcanic eruption and earthquake.
01:12:53In 1995, there was Kobe earthquake which killed about 6,000 people, but it was not predicted
01:13:05and all the seismological method failed to predict the earthquake.
01:13:12To predict earthquakes better, we have to know more about their causes. A capsule designed
01:13:20to travel to the center of the earth could help. If we weren't in a hurry, we could bury
01:13:27it in the Pacific plate and wait for a few million years. It would end up under Japan,
01:13:36courtesy of continental drift and subduction. The rock we parked the capsule in is solid,
01:13:44but also moving. This is what the mantle does. It flows very, very slowly at about a centimeter
01:13:51or so a year. But like glass, if you hit it with a hammer, it breaks.
01:13:59And that's what causes an earthquake. 150 miles down, one plate tries to move against
01:14:06another. Incredible pressure builds until one slab breaks and slips.
01:14:37Because of its unstable foundations, Japan has one of the most comprehensive networks
01:14:44of earthquake sensors in the world. 1,700 underground sensors listen out for a hint
01:14:53of movement in the crust and mantle. The data is beamed back to a national monitoring center
01:15:01that records every tiny moan and groan. Every quake, however small, is mapped in three dimensions.
01:15:13The quest is to find a pattern that will predict future quakes, because Japan is due another
01:15:20big one. It's expected here, Tokyo.
01:15:30Tokyo has a population of over 12 million. Every 200 years, this area is hit by a huge
01:15:43earthquake. The city is built over a busy intersection where four of the Earth's plates
01:15:53meet. The subterranean collisions never stop. That's why Japan's so prone to earthquakes
01:16:01and why it's so hard to see them coming. It's a high-stakes game. Millions could be
01:16:09hurt or killed. To get better data, they will have to drill down into the colliding plates
01:16:16more than six miles. JADS stands for Japanese Ultra Deep Drilling
01:16:22and Geoscientific Experiment. That is to drill about 10 kilometer hole down to the subduction
01:16:30zone. They've chosen a site, but what about the
01:16:34technology? The target area of the JADS project is very
01:16:38active and probably the temperature could be more than 300 degrees at the depth of 10
01:16:44kilometer. And then the 300 degree makes every operation of the drilling very difficult.
01:16:52And that's the same for our capsule. We'd need more technology for it to survive the
01:16:59intense temperature and pressure. What will the capsule find at the center of the Earth?
01:17:11A mammoth nuclear reactor?
01:17:22On its way to the center of the Earth, our capsule will have to navigate a sea of molten
01:17:30iron. Surging around the inner core, this generates magnetic energy. Just one percent
01:17:39of it escapes from Earth, but that's enough to form a protective shield 37,000 miles out
01:17:46into space. But how is so much energy produced? As Jeremy Bloxham admits, we're still struggling
01:17:55to find out. Really the burning question, which we all
01:18:03wish to address through our investigations of the Earth's magnetic field, is how is the
01:18:08field generated? What is the mechanism that gives rise to a field which has persisted
01:18:14for at least two billion years? One geophysicist has a radical suggestion.
01:18:23Marvin Herndon speculates that at the center of the Earth, we may find a natural nuclear
01:18:29reactor. One of the problems that has existed in science
01:18:36is figuring out what is the energy source that drives the Earth's magnetic field.
01:18:44He doubts that it's just a ball of iron that's been cooling for four and a half billion years.
01:18:49There's simply so much power, enough to maintain the magnetic shield, move continents, and
01:18:56make volcanoes and earthquakes. Herndon suspects there's something much more powerful down
01:19:03there. One of the implications that I suggested
01:19:07early on was the possibility that the changes that we observe in the geomagnetic field may
01:19:15have their origins in changes in the output power of the nuclear reactor.
01:19:23Could this explain the drastic changes our planet has gone through?
01:19:28Like the extinction of the dinosaurs?
01:19:39Could the melting of the ice caps have been caused by a surge of heat from a nuclear core?
01:19:46Because unlike an iron core, a nuclear one can fluctuate.
01:19:58While nuclear reactors can shut itself down and start itself up again, its output can
01:20:05vary, or it can remain very constant.
01:20:10Herndon's ideas are controversial. Few agree with his theory, and the debate continues.
01:20:16But one thing isn't disputed. The magnetic field is changing, and measurements show it's
01:20:23been doing so for some time.
01:20:26Based on the results in our current systems that are sort of, you know, basketball size,
01:20:32then we have this plan for a much larger system that would be 10 foot in diameter sphere,
01:20:38filled with liquid sodium, so about 15 tons of the metal.
01:20:42But it would be driven the same way as the existing experiments, but then at parameters
01:20:48that are much closer to the parameters thought to exist in the interior of the Earth.
01:20:56The capsule we built to journey to the center of the Earth is under its own power after
01:21:04hitching a ride in the rock.
01:21:15Now, sensors show the going is about to get tough.
01:21:261800 miles down, the capsule nears the boundary between the mantle and the outer core.
01:21:44The huge temperature here melts away the remains of the tectonic plate surrounding the capsule.
01:21:52Now, the capsule must be released from its protection and power itself.
01:22:01The capsule drives forward through the liquid outer core.
01:22:12Now, it must cut its way into the solid inner core.
01:22:17It's solid because there's massive pressure here, 4 million times greater than at the surface.
01:22:28And a billion amps of electricity surges between the cores.
01:22:36This, at last, is our journey's end, the center of the Earth.
01:22:42The only place on our planet with no gravity.
01:22:54Jules Verne's influence on the world has been immense.
01:22:59He propelled generations of young readers toward careers in science, engineering, and exploration.
01:23:11He inspired the inventors of the helicopter, the submarine, and the radio.
01:23:18There's little doubt that his novels influenced the minds that have changed our world.
01:23:25Little did anyone know, when Jules Verne died at the dawn of the 20th century,
01:23:30he was the first man to write a novel.
01:23:33His life is summed up in the inscription on his tomb,
01:23:36Onward to Immortality and Eternal Youth.
01:23:45If Jules Verne was right, maybe one day, we will be able to journey into the future.
01:23:51Onward to Immortality and Eternal Youth
01:23:58If Jules Verne was right, maybe one day, we will be able to journey to the center of the Earth.
01:24:21Onward to Immortality and Eternal Youth
01:24:25Onward to Immortality and Eternal Youth
01:24:29Onward to Immortality and Eternal Youth
01:24:33Onward to Immortality and Eternal Youth